1. Field
Example embodiments in general relate to a modular light emitting diode (LED) lighting fixture.
2. Description of the Related Art
Light emitting diodes (LEDs) are widely used in consumer lighting applications. In consumer applications, one or more LED dies (or chips) are mounted within a LED package or on an LED module, which may make up part of a lighting fixture which includes one or more power supplies to power the LEDs. The package or module in a lighting fixture includes a packaging material with metal leads (to the LED dies from outside circuits), a protective housing for the LED dies, a heat sink, or a combination of leads, housing and heat sink. Various implementations of the LED lighting fixtures including one or more LED modules are available in the marketplace to fill a wide range of applications, such as area lighting, indoor lighting, backlighting for consumer electronics, etc.
Conventional area lighting such as roadway lights uses high pressure sodium (HPS) bulbs which provide omni-directional light. Reflectors are used to direct some of this light, but much of the light is lost illuminating unintended spaces. For example with HPS bulbs, the typical lumen amount will be in the tens of thousands of lumens, but all of that output does not illuminate the intended area, such as a roadway area for example.
LEDs offer improved light efficiency, a longer lifetime, lower energy consumption and reduced maintenance costs, as compared to HPS light sources. Conventional HPS bulbs are susceptible to maintenance loss and surface, dirt and other losses. Conventional area lighting fixtures are attached on poles, include omni-directional HPS bulbs, and employ reflectors to illuminate the roadway in different patterns based on different situations.
FIGS. 7A to 7G show types of roadway illumination. The Illuminating Engineering Society of North America (IESNA) is the recognized technical authority on illumination and puts out specifications for the five primary types of roadway illumination. As shown in FIGS. 7A to 7G, there are five primary types of roadway illumination. Type I illumination is a direct illumination in two directions along the direction of the roadway (if the road is a single road) and/or in a straight directional pattern at a cross section as shown in FIG. 7B. FIG. 7C shows an Omni directional lighting pattern across the entire intersection, and Fig. shows a lighting fixture which directs light at an angle to normal in either two directions, or in four directions as shown in FIG. 7E.
Type III illumination in FIG. 7F shows a different angled illumination from normal as compared to Type II in FIG. 7D, where the angle of illumination from normal is narrower to reflect a smaller coverage area. Type IV illumination (FIG. 7G) has an even narrower angle of illumination from normal to create a different, smaller illumination area than either Type III or Type II.
Conventionally, these HPS lighting fixtures must be replaced with a completely different fixture to change the lighting pattern at a given location. In order to change the shape and brightness of light output from the HPS fixture, there is no way to alter the pattern other than replacing the entire fixture. Similarly for LED lighting fixtures mounted on poles for area lighting applications, the entire fixture must be replaced in order to change the shape and brightness.